<!DOCTYPE html>
<html>

<head>
    <style>
        .bg {
            height: 200px;
            background-color: aqua;
        }

        div.box {
            /* box-sizing: border-box; */
            width: 200px;
            height: 200px;
            float: left;
            background-color: #ffa700;


            border: 20px solid red;

            padding: 5px;

            /* margin: 5px; */
        }
    </style>
</head>

<body>



    <div class="bg">
        <div class="box">
            盒子文字
        </div>
    </div>



</body>

</html>